Electromotive device



G. M. ALBRECHT.

ELECTROMOTIVE DEVICE.

Patented June 22, 1920.

APPLICATION FILED MAY 27. I918.

UNITED s'r rrs PALIENVT OFFICE.

I GEORGE M. ALBRECHT, 0F MILWAUKEE, WISCONSIN, ASSIGNOR TO ALLIS-CH.A.I.|MERS MANUFACTURING COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF DELAWARE.

ELEGTROMO'IIVE DEVICE.

Specification of Letters Patent. Patented J 22 1920 Application filed May 27, 1918. Serial No. 236,950.

new and useful Improvement in Electro motive Devices, of which the following is a specification.

This invention relates to electromotive devices and may be applied, for example,

for driving the movable element of relay devices and more particularly such devices used for closing the trip coil circuit of a circuit breaker under abnormal conditions,

as overload for example.

It is most convenient to describe the dcvice in connection with one of its uses. In systems of distribution supplying translatincr devices, overloads frequently occur but t ese are usually dangerous only if they continue for a predetermined time. It is thus not desirable to interrupt the currentsupply to a translating device or feeder as soon as there is excessive overload as the overload may be only momentary and thus no damage will be caused. It is furthermore desirable that the circuit be inter:

rupted after the occurrence of an abnormal condition in times inversely proportional to the abnormality of the condition but when the latter exceeds a given value it is further desirable, in order that all of the relays on a system do not operate at once, to obtain actuation in a constant time irrespective of the abnormality of the condition. Each relay can thus be set for a different constant time and they will thus be selective in their action, only the circuits nearest the'overload or short circuit being opened. It is obvious that in order to secure results of this character, the controlling characteristic of the motive device can not be a linear function of the abnormal Another object is the provision of a de-.

vice which will execute its effective movement after the occurrence of an abnormal condition in times inversely proportional to the abnormality of the condition up to in the claims."

a certain predetermined condition and above that condition to execute its effective movement in a substantially predetermined constant time. 1

Another object isthe provision of devices of the above noted character in which-varying control is obtained without the use of movable parts or contacts. jects will appear hereinafter as the description of the invention proceeds.

The novel features of the invention will be apparent from this specification and the Other obaccompanying drawings which form a part thereof and Will be In Figurel, a diagrammatic view partly inperspective, the invention is shown as it may be applied in a relay of the alternating current type.

Fig. 2 is a side elevation in detail of a fragment of the electromotive device of Fig.

1. Fig. 3 is a diagrammatic view of a modification. 1

In Fig. l a circuit breaker 1 is shown in the three phase lines 2, 3, 4, and an actuating electromagnet 5 may be inserted in one of the lines 2. 'The magnet 5' is wound on a U-shaped core 6 havin legs 7 8, and the legs 7, 8, are provide with polar portions 9, 10. The air gap between the polar portions 9, 10, is here shown as narrowest at the points 11, 12, of these polar portions. If desired, one of the polar portions 9 may be bentor cut away as more clearly shown at the point 13, Fig. 2. The polar portions may be provided with shading coils. In the devices shown, the polar portion 10 has been provided with two shading coils 14, 15.. The shading coil 15 is here shown somewhat smaller than the coil 14 for reasons which will be hereinafter noted. The polar portion 10 is pro- *vided with notches or cuts 16, 17, located between the source of flux, which here is the coil 5, and the shading coil 15. These notches or cuts are also shown in Fig. 2 and their purpose will be moreparticularly explained in connection with the description of the operation of the device.

A conducting disk 18 is provided which may be disposed between the polar portions 9, 10; The disk is shown as partly broken. awayin order to more clearly indicate the polar portions-of the U-shaped core. A per.

particularly pointed out:

manent magnet 19 or other magnet may be provided for retarding the motion of the disk 18. The disk 18 is mounted for movement in any suitable manner on a shaft 25. The movement of the shaft and consequently the disk is retarded by means of a spring 20. The shaft 25 may have mounted thereon at any suitable point a contact 21 which is adapted, after the shaft and disk have rotated a predetermined angular distance, to make contact with a relatively stationary contact 22. The relatively stationary contact 22 is preferably mounted so as to be adjustable on or with shaft 26. The

position of the contact 22 may be adjusted by a handle or indicator 27 which latter coiiperates with a scale 28 to indicate the position of the contact. The scale 28 may be calibrated in seconds. When the contacts 21 and 22 engage, they close the circuit of the trip coil 23 of the circuit breaker 1 through any suitable source of current 24 thus opening the main lines 2, 3, 4t.

The operation of the device is as follows:

\Vhen a current flows through the coil 5 which does not exceed the normal load the system is designed to carry, the coil 5 will generate a predetermined amount of flux. This flux will pass freely from the upper portion, for example, of the core portion 6 through leg 8 along the dotted lines 29, 30, 31, passing from the polar portion 10,

through the conducting disk 18", to the lower.

polar portion 9, through the leg 7 to the lower end of the core portion 6. The flux also passes freely through all of that side of the polar portion 10 upon which the larger shading coil 14 is located and thus flux normally threads through this shading coil 14 and induces a current therein. The current induced in the disk by the flux passing through the said disk as described above, in conjunction with the flux produced by the current in the shading coil 14, produccs a torque on the conducting disk 18 in a predetermined direction, but inasmuch as the spring 20 is of suflicient strength to resist this torque no motion of the contact 21 will be produced under normal conditions of current flow in coil 5.

Normal flow of flux is however somewhat different in that side of the polar portion 10 which carries the smaller shading coil 15. This is better illustrated in Fig. 2 in conjunction with Fig. 1. It will be seen that as flux proceeds from the upper portion of core portion 6 along the dotted lines 32, 33, it encounters an air gap caused by the notch or cut 17. Referring now to Fig. 2, the normal path of flux may be traced in the leg 8 along the path 34, to the restricted portion 40, across the air gap 35, along the path 36 of the leg 7 returning through the same to the core of the coil. It will be noted that ,the path just traced is the path of lowest reluctance under normal conditions for the reason that if the flux attempts to pass beyond the restricted portion 40, it will have to assume the path 37 which is an air gap considerably longer than the air gap and therefore no flux will pass in that direction. Furthermore the flux will not pass through the iron path 88 for the reason that in order to go from pole 10 to pole 9 along this path, the air gap 39 must be crossed which is longer than the air gap 35. The flux will not pass from the leg 8 directly into the upper end of the polar portion 10 for the reason that to do so it would have, to jump the notch or cut 17. It will thus be seen that under normal conditions practically all of the flux will pass across the air gap 35 and substantially none of it will reach and thread through the shading coil 15, all of the possible paths to this 0011 involving a path of much greater reluctance.

If the system is overloaded, causing more than a normal flow of current in coil 5, a

sufficient amount of flux will be produced to cause enough induced current in the disk 18 and the larger shading coil 14; to produce a torque sufiicient to overcome the restraint of the spring 20. The contact 21 will therefore be moved into engagement with contact 22 in a predetermined time. If the overload is heavier the torque produced by the larger coil. 14- will be greater and the contact will execute its effective movement in a shorter time. The operation will take place in a similar manner with still higher overloads up to a certain predetermined degree. p to a redetermined degree of overload there will be no change in the dis tribution, of flux in the side of the polar portion 10 on which the smaller shading coil 15 is mounted.-

If however, the current in the coil 5 exceeds a predetermined excessive value, the restricted portion 10 will become saturated and the path 38, 39, and the path 34, 17, 38, 39, will no longer be of comparatively higher reluctance than the normal path across the gap 35 and if the portion 40 is suiliciently saturated a great deal of the flux will pass through the paths noted and thread through the coil 15, the lines of course extending to the outer end of the polar portions 9, 10, and as a result, current will be induced in the smaller coil 15, and inasmuch as this coil isoppositely disposed to the flux passing through the middle of the polar portion 10, it will, in conjunction with the currents induced in the disk by that flux, produce a torque on the disk 18 in opposition to the torque produced by the larger coil 14. In View, however, of the fact, that the coil 15 is of somewhat smaller area than the coil 14. the torque produced will not be so great. Furthermore not quite as much flux will pass through the smaller coil 15 under excessive abnormal conditions as passes through the larger coil 14.

It will be apparent therefore that under very excessive normal conditions the torque produced on the disk 18 will no longer increase in proportion to the increase in current flowing in coil 5 and consequently the contact 21 will no longer execute its effective movement in times inversely proportional to the abnormality of theelectrical conditions. Inasmuch asthe smaller coil 15 produces a torque upon the disk 18, the

value of which for excessive amounts of overload is proportional to the excess of the overload and this torque is in opposition to the torque produced by'larger coil 14, the resultant torque of the two coils on the disk 18 will become substantially constant for I such excessive values of overload and consequently the contact 21 will execute its efiective movement in a substantially constant time irrespective of the amount of excess overload. The time elapsing between the occurrence of an abnormal condition 'and the tripping of a circuit breaker may be regulated by adjustment of the contact 22.

It will be noted that the magneticcircuit' for the smaller shading coil 15 is normally of higher reluctance than the magnetic circuit for the shading coil 14. The higher reluctance may be secured in any'desirable fashion and in the drawings it is, enerally ny 'forspeaking, of zig zag formation. mation, however, which'will normally prevent the passage of flux through the shading coil and permit its passage under abnormal conditions will come within the scope of the invention.

In Fig. 3 is shown a modification of the invention in which 141 isa shading'coil corresponding to the larger shading coil 14 of Fig. 1 disposed on the polar portion 101 corresponding to, polar portion 10 of Fig. 1. Instead of a solid conducting .member, smaller' shading coil 15 ofFig. 1 has been replacedv in Fig. 3 by a suitably. propon tioned coil 151 in series with which is a resistance 42 which may be adjusted by means of a contact arm 43. The notches .or cuts 171, 161, correspond to the similar ones 17,

16, shown in Fig. 1.v The legs71,.81, and

the polar portion 91correspond to the simi* lar parts 7, 8, 9 of Fig. 1.

The actuating magnet core has been omitted in Fig. 3 as. have also the remaining elements constitutin the res lay, as they may be the same as in of any desired form.

The operation of an electromotivedevice *ig. 1 or provided with such an actuating structure as shown in Fig. 3 is exactly the same asdescribed in Fig. 1 except that the amount of current which is induced in the shading coil 151 may be regulated by adjusting the for the lJ-shaped resistance 42 and therefore the opposing torque produced by this shading coil may be varied. It is clear that a variation of this opposing torque for any predetermined value of current flow in thecoil 5 will vary the resultant torque, on the disk 18 and consequently the time elapsing between the initiation of movement and the engagement:

of contact 21 with contact 22.

\ It should be understood that it is no I desired. that the invention claimed be limited to the exact details of construction as shown'and described for obvious modifications will occur, to a person skilled in the art.

-. It is claimed and desired to secure by Let f ters Patent-z I I i In. combination with an electrical circult, an electromagnet'responding to current in' said circuit having'pole pieces, a movable conductingdisk disposed between said pole pieces, a shading coil on one of said pole in one direction,a secondshading coil on said polepiece for producing a 'torqueon said disk in the other direction," and means pieces for producing a torque on said disk for preventing action of one of said shading coils untilthe current in said circuit has reached a predetermined value.

2; In an electromotive device, a magnetic circuit having a gap, a movable conducting member disposed in said gap, magnetomotive force-producing meansfor energizing said magnetic circuit, means responding to flux in said magnetic circuit forcausing torque to be produced in one direction on said movable member, and normally inactive means responding to a predetermined increase in magnetomotive force in said mag-n netic circuit for causing torqueto be pro duced on said movable member in the other direction. y v f 3. In an electromotive device, a magnetic 'c1rcuit having a gap, a movable conducting member disposed in said gap, magnetomotive force-producing means for energizing said magnetic circuit, means responding to flux in said magnetic circuit for causing a torque to be produced on said disk in one direction, and means dependent upon a change in the distribution of flux caused by ,a predetermined increase of magnetomotive force for causing a torque to be produced in the other direction. 1

4. In an electromotive device, a'magnetic circuit having a gap, a movablejconducting member disposed in said gap, magnetomotive force-producing means for energizing said magnetic clrcuit, means responding to fluxin said magnetic circuit for. causing a torque to be producedon said movable memberfin one direction, and means dependent upon a 'changein the distribution of flux caused by a predetermined increase 05 ber disposed between said pole pieces, two

magnetomotive force for causing a torque to be produced in the other direction of less determined torque upon said movable member in a given direction, for certain values of current in said circuit and producing two opposed torques having a resultant acting in the same direction as the first named torque for other values of current of the same frequency.

6. In a protective device, a movable conducting member, a winding connectible to carry current varying in the same sense as current in an electrical circuit, means responsive to current in said winding for producing torques upon said movable member of increasing value as the current increases and for producing two opposing torques at predetermined higher values of current whereby the resultant torque remains substantially constant irrespective of said higher current values.

7. In an electromotive device, an electromagnet having a winding and two unitary polar faces, two shading coils associated with one of said polar faces, a movable conducting member disposed between said polar faces, the reluctance of the magnetic circuit of one of said shading coils being greater than that of the other.

8. In a protective device, two parallel magnetic circuits having an air gap, a movable conducting member disposed therein, means for energizing said magnetic circuits, a shading coil for each of said circuits, means in one of said circuits between one of said shading coils and said energizing means for predetermining the relative reluctance of said circuits irrespective of the frequency of the energizing current.

9. In a protective device, a magnet having pole pieces, a movable conducting member disposed between said pole pieces, two shading coils at one end of one of said pole pieces, one coil being on each side of said pole, and a cut in said last named pole piece facing the other pole piece disposed near one of said coils, said cuts being of a length less than the width of said pole piece.

10. In a protective device, a magnet havs'hading coils at one end of one of said pole pieces, one coil being on each side of said pole, and oppositely disposed nonregistering cuts in said last named pole piece disposed near one of said coils, said cuts being of a length less than the width of said pole piece.

11. In an electromotive device, a magnet comprising a core, and a coil thereon, pole pieces for said magnet, magneto-responsive means near the end of one of said pole pieces, one of said pole pieces being of zigzag formation between said means and said coil.

12. In a protective device, a magnet comprising a coil and pole pieces, a movable conducting member disposed between said pole pieces, two magneto-responsive means at one end of one of said pole pieces, one magneto-responsive means being on each side of said pole, said pole piece being of zig-zag formation between one of said means and said coil, said formation extending less than the width of said pole piece.

1.3. In a protective device, a movable conducting member, a winding connectible in an electric circuit, means for causing said movable conducting member to execute its effective movement in times inversely proportional to current flowing in said circuit up to a predetermined value of current and in a substantially constant time for greater values of current, comprising means responsive to current in said winding for producing a torque upon said movable mem ber for certain values of current in said circuit and producing two opposed torques for other values of current.

1 1. In a protective device, a'movable conducting member, a winding connectible in an electric circuit, means for causing said movable conducting member to execute its effective movement in times inversely proportional to current flowing in said circuit up to a predetermined value of current and in a substantially constant time for greater values of current, comprising a core encrgized by said winding, said core having pole pieces between which said movable member is disposed, two shading coils on one of said pole pieces, the reluctance of the magnetic circuit of one of said shading coils being greater than that of the other.

15. In a protective device, a movable conducting member, a winding connectible in an electric circuit, means for causing said movable conducting member to execute its effective movement in times inversely proportional to current flowing in said circuit up to a predetermined value of current and in a substantially constant time for greater values of current, comprising two parallel magnetic circuits having an air gap between which said movable member is disposed, said magnetic circuits being energized by said winding, a shading coil for each of said circuits, and means in one of said circuits between one of said shading coils and said winding for increasing the reluctance of the last named circuit.

16. In a protective device, a movable conducting member, a winding connectible in an electric circuit, means for causing said movable conducting member to execute it's eliective movement in times inversely proportional to current flowing in said circuit up to a predetermined value of current and in a substantially constant time for greater values of current, comprising a magnetic circuit energized by said winding having a gap between which said movable member is disposed, means responding to llux in said magnetic circuit for causing torque to be produced in one direction on said movable member, and normally inactive means responding to flux in said magnetic circuit for causing torque to be produced on said movable member in the other direction.

17 In a protective device, a movable conducting member, a winding connectible in an electric circuit, means for causing said movable conducting member to execute its eilective movement in times inversely pro"- portional to current flowing in said circuit up to a predete ined value current and in 11- substantially constant time for greater values of current, comprising a magnetic circuit energized by said winding having a gap between which said movable member is disposed, means responding to flux in said magnetic circuit for causing torque to be produced in one direction on said movable member, and means dependent upon the distributionof flux for causing a torque to be produced in the other direction.

18. In a protective device, a movable conducting member, a winding connectible in an electric circuit, means for causing said movable conducting member to execute its effective movement in times inversely proportional to current flowing in said circuit up to a predetermined value of current and in a substantially constant time for greater values of current, comprising a magnetic circuit energized by said winding having a gap between which said movable member is disposed, means responding to flux in said magnetic circuit for causing torque to be produced in one direction on said movable member, and means dependent upon the distribution of flux for causing a torque to be produced in the other diinction of less magnitude than the first torque.

- In testimony whereof the signature of the inventor is aflixed hereto.

GEORGE M. ALBRECHT. 

